A vaporizer for an anesthetic medium is disclosed in U.S. Pat. No. 4,017,566. This vaporizer includes a bypass connected in parallel to the vaporizing chamber. To maintain the quantity of the vaporized anesthetic medium so as to be as independent as possible from the temperature of the apparatus, the gas quantity flowing through the bypass is controlled by changing a throttle gap in dependence upon the temperature of the apparatus. In this vaporizer, the high thermal expansion of the interconnected housing parts of the vaporizing chamber and of the adjusting device connected to the vaporizing chamber are utilized to control the width of the throttle gap. A temperature-dependent throttle-gap width is obtained by connecting components having a low thermal coefficient of expansion. The housing parts are made of brass and have a very complicated configuration with narrow inner contours.
Since anesthetic media are very corrosive, the housing must be protected against corrosion by providing a nickel coating for example. However, this is at best unsatisfactory because of the complicated geometry of the assembly parts conducting the anesthetic gas. The component parts defining the throttle gap are provided with layers of different thicknesses because of the nickel plating which layers are measured with respect to the required tight tolerances. Since these layers are not adequately uniform, a dosage having the required accuracy can only be assured with difficulty.